1. Field of Invention
The invention relates to a reclining device, and more particularly to the setting of a free zone of a seat back.
2. Description of Related Art
A reclining device of a certain type is constructed as follows. First of all, a pawl having outer teeth on the side of a leading end thereof is brought into mesh with inner teeth of a ratchet on the side of an inner periphery thereof, so that a seat back is locked with respect to a seat cushion. Then, the seat back is unlocked with respect to the seat cushion by bringing the pawl out of mesh with the ratchet, so that the seat back can be tilted.
A reclining device of this type makes it possible to enhance locking strength of the seat back with respect to the seat cushion by enhancing meshing strength between the pawl and the ratchet. Therefore, as proposed, e.g., by Japanese Patent Application Laid-Open No. 6-125821, there is a reclining device employing a plurality of pawls to enhance meshing strength between the pawls and a ratchet. The reclining device of this type necessitates a range where the pawls are out of mesh while the ratchet is within a predetermined angular range, i.e., a free zone. The reclining device proposed by the aforementioned publication adopts a means of forming a free zone by introducing an unlatching ring.
In the reclining device of this type, the meshing strength between the pawls and the ratchet can be enhanced in proportion to an increase in the number of pawls to be employed. However, if the number of pawls is increased, a convex portion for setting a free zone cannot be formed on the unlatching ring for bringing the pawls out of mesh. This is because the convex portion for setting a free zone of a certain one of the pawls is located at a position where the pawls adjacent thereto are to be brought into mesh. This problem becomes all the more serious as the number of pawls increases or as the angular range of the free zone widens.